The present invention relates, in general, to simulation software and, more particularly, to the simulation of direct liquid cooling procedures to determine proper operating conditions for two-phase liquid cooling of integrated circuits.
High power single chip and multichip products demand advanced thermal packaging design to maintain circuit junction temperatures within an allowable range. These high power products include emitter coupled logic (ECL) gate arrays, BIMOS gate arrays, high end microprocessors, etc. Due to the nature of high power dissipation, i.e., circuit surface heat flux in the range of thirty to sixty watts per square centimeter, conventional air-cooled and indirect water cooled multichip module (MCM) packages may not be appropriate. Direct liquid cooling with phase change, or "two-phase liquid cooling", offers the most efficient heat transfer process and thus is one of the alternatives for advanced MCM thermal design. With phase change, i.e., from liquid to vapor, nucleate boiling at the surface of the integrated circuit package enhances heat transfer. This enhancement results in stable junction temperatures even under conditions of high surface heat flux.
In the past, optimizing the operating conditions for two-phase liquid cooling was a laborious, time consuming process. For each cooling scheme, whether by immersion, flow, jet impingement, or any other possible cooling method, a separate test fixture had to be manufactured. In the case of jet impingement, several different fixtures had to be constructed, representing different jet nozzle configurations. For each individual fixture, a matrix of experiments was performed. Different devices of different sizes and having different power dissipations were tested using a variety of different liquid coolants. For each liquid coolant, a matrix of temperatures and flow rates were tested at multiple system pressures. Physical observation was used to determine if the device under test was operating under nucleate boiling conditions. Testing the limits of cooling capability sometimes led to destruction of the device under test. The amount of work involved prevented making truly accurate determinations as to optimum cooling scheme, fluid temperature, and flow rate.